Support the authenticationCleartextPassword message

[RobinClowers]

I'm trying to connect this tool to a Materialize database, which only supports clear text passwords (but only over ssl). I see that your pgwire implemenation expects this message:

pgtyped/packages/query/src/actions.ts

Line 50 in 929fe3a

messages.authenticationCleartextPassword,

But it doesn't appear to actually do anything in that case, the rest of the code in that function deals with sasl and md5, unless I'm missing something.

Describe the solution you'd like
Support for the clear text password authentication mechanism.

[RobinClowers]

This appears to be extremely simple and works in my testing, check out #502